Gating properties of gap junction channels assembled from connexin43 and connexin43 fused with green fluorescent protein

Biophys J. 2001 Jul;81(1):137-52. doi: 10.1016/S0006-3495(01)75687-1.


We used cell lines expressing wild-type connexin43 (Cx43) and Cx43 fused with enhanced green fluorescent protein (Cx43-EGFP) to examine mechanisms of gap junction channel gating. Previously it was suggested that each hemichannel in a cell-cell channel possesses two gates, a fast gate that closes channels to a nonzero conductance or residual state via fast (< approximately 2 ms) transitions and a slow gate that fully closes channels via slow transitions (> approximately 10 ms). Here we demonstrate that transjunctional voltage (V(j)) regulates both gates and that they are operating in series and in a contingent manner in which the state of one gate affects gating of the other. Cx43-EGFP channels lack fast V(j) gating to a residual state but show slow V(j) gating. Both Cx43 and Cx43-EGFP channels exhibit slow gating by chemical uncouplers such as CO(2) and alkanols. Chemical uncouplers do not induce obvious changes in Cx43-EGFP junctional plaques, indicating that uncoupling is not caused by dispersion or internalization of junctional plaques. Similarity of gating transitions during chemical gating and slow V(j) gating suggests that both gating mechanisms share common structural elements. Cx43/Cx43-EGFP heterotypic channels showed asymmetrical V(j) gating with fast transitions between open and residual states only when the Cx43 side was relatively negative. This result indicates that the fast V(j) gate of Cx43 hemichannels closes for relative negativity at its cytoplasmic end.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Carbon Dioxide / pharmacology
  • Cell Line
  • Connexin 43 / genetics
  • Connexin 43 / metabolism*
  • Electrophysiology
  • Female
  • Gap Junctions / chemistry*
  • Gap Junctions / genetics
  • Gap Junctions / metabolism*
  • Green Fluorescent Proteins
  • HeLa Cells
  • Heptanol / pharmacology
  • Humans
  • Ion Channel Gating / drug effects
  • Ion Channels / chemistry
  • Ion Channels / genetics
  • Ion Channels / metabolism
  • Kinetics
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Microscopy, Fluorescence
  • Rats
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / metabolism


  • Connexin 43
  • Ion Channels
  • Luminescent Proteins
  • Recombinant Fusion Proteins
  • Carbon Dioxide
  • Green Fluorescent Proteins
  • Heptanol